This invention relates to sealing devices of the type in which a member of rigid material, such as metal or plastic, has a circumferentially extending groove therein that receives an elastomeric packing. One sealing device of this general type is shown in U.S. Pat. No. 2,717,793. In this patent the sealing device is in the form of a flat plate with an opening therethrough and having grooves on both sides of the plate which surround the opening and contain the resilient packings. The device serves as a flat gasket to seal between flat planar faces of pipe flanges, cylinder blocks and heads, and other devices having fluid passages to be sealed. The packings are molded into the grooves and have portions projecting therefrom. Each packing has a pair of recesses extending into the respective groove with the volume of the projecting portion being substantially the same as the volume of the recesses whereby upon clamping the gasket between the members to be sealed, the projecting portions make sealing contact with the members and are deformed to substantially fill the recesses.
In the past it has been desired to utilize the sealing principles of U.S. Pat. No. 2,717,793 for access doors on various structures. In such cases, the rigid member has no opening and a packing is mounted on only one face of the door. When the doors are flat and planar, the exact configuration of the packing shown in U.S. Pat. No. 2,717,793 may be used. However, when the doors are curved in one direction, as in the case of a door in the form of a portion of a cylinder which is to be mounted on a cylindrical member, such as a cylindrical missile housing, it is not practical to mold the packing configuration of U.S. Pat. No. 2,717,793 into the curved door because portions of the recesses in the packings will have an undercut relation to the direction of travel of the one mold member relative to the other with the result that the packing will be damaged when the mold members are separated after the molding operation. To overcome this problem it has heretofore been the practice to make the doors flat, mold the packing into the door groove, and then bend the door to the desired curvature. This is a costly procedure that is difficult to accomplish properly, particularly if the door has reinforcing webs. Therefore, it is an object of this invention to provide a packing configuration that has no undercuts when molded into a groove in a door that is already curved so that the mold members may be separated after the molding operation without damaging the packing.
U.S. Pat. No. 2,995,057 illustrates a bolt with a resilient packing molded in place within a groove in a frustoconical surface of the bolt head. The packing has a recess and a projecting portion which do not form undercuts relative to the direction of travel of the mold members when separating but the patent does not disclose how a packing ring may be molded into a rigid member that is a portion of a cylinder without forming undercuts in the packing which would prevent separation of the mold members without damaging the packing.
The present invention provides a packing configuration that may be used for packings molded into a continuous, generally annular groove in either a rigid door member or a rigid gasket member that has been preformed in the form of a portion of a cylinder, that is, a form which in one cross section presents a curved outline and in another cross section normal to the first cross section presents a straight outline. This is accomplished by providing the packing with a configuration that has no undercuts relative to the direction of mold separation travel. The packing has a portion that projects from the receiving groove and includes a single recess extending into the groove for receiving the projecting portion when the latter is deformed into sealing contact with the member to be sealed. The packing further includes a surface extending from the bottom of the recess to the projecting portion. This surface in all locations about the circumference of the packing is either parallel to or inclined outwardly relative to a transverse axis of the rigid member whose direction corresponds with the direction of travel of the one mold member when it separates from a companion mold member. This packing surface forms one side of the recess in the packing. The other side of the recess is likewise so formed that it will provide no undercut which would otherwise interfere with separation of the molds.
The groove for receiving the packing may be on either the concave or convex surfaces of the curved door. In the case of a gasket there may be a groove on both the convex and concave surfaces.